Conventionally, regarding a solid-state imaging device, noise reduction function is important to obtain a high-quality image. Known main noises that affect imaging by a solid-state imaging device include pixel-based noise caused by a pixel and circuit-based noise caused by a circuit. Random noise is dominant in the pixel-based noise. The circuit-based noise may appear as a fixed pattern such as a horizontal line and a vertical line. These types of noise are reduced by improving a circuit configuration and by process tuning.
In recent years, noise reduction processing technology has progressed. Thus, it is difficult to adjust the balance between tuning of the pixel-based noise and tuning of the circuit-based noise. In the case where the random noise is prominent compared with the fixed pattern noise and the fixed pattern noise is buried in the random noise, the pixel-based noise is dominant as noise in the solid-state imaging device. In this case, in the case where the random noise is reduced by tuning the pixel-based noise, the fixed pattern noise becomes dominant. In the case where the fixed pattern noise is reduced by tuning the circuit-based noise, random noise becomes dominant. Since the circuit-based noise and the pixel-based noise need to be tuned while adjusting the balance of these noises, time and effort are spent on the process tuning.
In a low illumination scene, the small number of electrons generated by a pixel cause the small range of variation in random noise. Furthermore, in a low contrast scene, the fixed pattern noise becomes conspicuous. In this case, the fixed pattern noise becomes significant. Additionally, the more the signal-to-noise ratio of a pixel improves, the more the circuit-based noise becomes conspicuous compared with the pixel-based noise. In the case where the balance between the pixel-based noise and the circuit-based noise is adjusted, the pixel or the circuit may be used with lower characteristics compared with actually obtained characteristics.